Kinetic exchange vs. room temperature ferromagnetism in diluted magnetic semiconductors

Guided by the internal-reference rule and the known band offsets in III-V and II-VI diluted magnetic semiconductors, we discuss the feasibility of obtaining p-type conductivity, required for the carrier-induced ferromagnetism, as well as the cases for which the doping by shallow impurities may lead to the ferromagnetism driven by the double exchange. We consider the dependence of kinetic exchange on the p-d hybridization, on the electronic configurations of the magnetic ions, and on the energies of the charge transfer between the valence band of host materials and the magnetic ions. In the case of Mn-based II-VI compounds, the doping by acceptors is necessary for the hole-induced ferromagnetism. The latter is, however, possible without any doping for some of Mn-, Fe- or Co-based III-V magnetic semiconductors. In nitrides with Fe or Co carrier-induced ferromagnetism with T_C>300K is expected in the presence of acceptor doping.